N.B. The prices in Jersey / Guernsey are tax free (afik) so I suppose are not really comparable.

The Shell Price List states that Avgas is available from them on the Apron of Cork Airport for €176 per 100 litres. They don't state if their values are excluding or including VAT but they are most likely excluding VAT, so the VAT inclusive value is €2.16 per litre.